Perhaps I’m not making myself clear… Virtual Insanity…

What is it with virtualization? It’s like people remove their brain as soon as they hear the word. I get a lot of questions about virtual RAC installations and the vast majority of problems are due to people trying to run them on a host that can’t cut it.

When I explain you need 3-4G RAM for each VM node in a VirtualBox RAC installation, would you consider it sensible to try and build a 3 node virtual RAC on a host with 8G RAM? Do the maths. If you are attempting a virtual 11.2 installation with less than 3G RAM per node and you have problems, don’t come asking me because I will be out.

Do you really expect disk speed to be good when you put 8 virtual disks on to the system disk on the host machine? Do you think virtual disks magically run independently of the hosts disk subsystem? Putting all the virtual disks on one physical disk will work, but it will be so darn slow you will probably be leaving installations running overnight. Believe me, I’ve done it. If you want any sort of speed, spread the virtual disks around on separate physical disks.

Yes, you really are going to need all those IP addresses. Deal with it.

Use DNS or accept the fact there will be SCAN configuration errors during the installation. It’s one or the other baby!

Have you really done what my article suggests? Normally, after about a week of going back and forward I get a message saying something like, “Oh I fixed it. I didn’t bother doing step X before and once I did it it worked fine.” Don’t waste my time and yours. Follow the steps, or do it your own way and don’t blame me if it doesn’t work.

Use the same software I list in the installation. Don’t just assume that if it works fine with OL 5.x it’s going to work unchanged on OL6, SUSE x.x or Ubuntu (Lethargic Leaper) etc. If you want to try with different distributions that’s fine, but I’m probably not going to be able to help you because if there isn’t an installation guide for it on my site, it probably means I’ve not done it.

If it is the first Oracle installation you’ve ever done, don’t start by trying to install a virtual RAC. Learn to walk before you try running…

The last point is the crux, I think. Too many people don’t realise RAC is a different animal and they want to go from newbie to installing a cluster, thinking it’d be easy. So many people want to take shortcuts now…